Docs: How-it-works covers Lightning/Ark/SP/gifts; README rewrite

The in-app page grows plain-language cards for Lightning swaps, Ark
(instant off-chain, the unilateral escape hatch, expiry housekeeping,
fees), silent payments, and gift links. The README catches up with
reality: the native-JS Ark client headlines the feature list, and the
modular HAL_FEATURES build system gets its own section — every feature
is a plugin behind a build seam, and excluded code never ships.

Co-Authored-By: Claude Fable 5 <[email protected]>

2 files changed, 26 insertions, 2 deletions

diff --git a/src/app.js b/src/app.js
index 7eacff1..fa0fe90 100644
--- a/src/app.js
+++ b/src/app.js
@@ -504,9 +504,23 @@ function howItWorksScreen() {
       para('hiwBasics2'),
       para('hiwBasics3'),
       para('hiwBasics4'),
-      para('hiwBasics5'),
-      h('p', { class: 'small muted hiw-tribute', style: 'margin:0' }, ...linkify(t('hiwTribute')))
+      para('hiwBasics5')
     ),
+    h('div', { class: 'card col', style: 'gap:14px' },
+      h('h3', {}, '⚡ ' + t('hiwLnTitle')),
+      para('hiwLn1')),
+    h('div', { class: 'card col', style: 'gap:14px' },
+      h('h3', {}, '⚔ ' + t('hiwArkTitle')),
+      para('hiwArk1'),
+      para('hiwArk2'),
+      para('hiwArk3')),
+    h('div', { class: 'card col', style: 'gap:14px' },
+      h('h3', {}, '👤 ' + t('hiwSpTitle')),
+      para('hiwSp1')),
+    h('div', { class: 'card col', style: 'gap:14px' },
+      h('h3', {}, '🎁 ' + t('hiwGiftsTitle')),
+      para('hiwGifts1'),
+      h('p', { class: 'small muted hiw-tribute', style: 'margin:0' }, ...linkify(t('hiwTribute')))),
     h('button', { class: 'btn-block', onClick: back }, t('back'))
   );
 }
diff --git a/src/i18n.js b/src/i18n.js
index 586bacb..e45d662 100644
--- a/src/i18n.js
+++ b/src/i18n.js
@@ -129,6 +129,16 @@ const STR = {
     hiwBasics3: 'There’s no server and no account. The whole app is a single page that runs in your browser, so nobody holds your coins and nothing on a server ever sees your keys. To show your balance and history it reads from a public block explorer (mempool.space by default, or your own node if you set one in Settings).',
     hiwBasics4: 'You can even save this page and open it straight from your computer with no internet at all. It keeps working offline.',
     hiwBasics5: 'It follows the usual Bitcoin standards (a 12-word BIP39 phrase and BIP84 native SegWit keys), so if this site ever disappears you can restore the same phrase in Sparrow, Electrum, or any other standard wallet and your coins will be right there.',
+    hiwLnTitle: 'Lightning',
+    hiwLn1: 'You can pay Lightning invoices and receive Lightning payments. Behind the scenes a swap provider exchanges between your on-chain coins and Lightning without ever holding your money — if a swap fails, the coins come back to you. A small swap fee applies, shown before you confirm.',
+    hiwArkTitle: 'Ark',
+    hiwArk1: 'Ark is a newer way to pay off-chain: sends arrive instantly, cost no mining fees, and stay self-custodial. You "board" coins from your on-chain balance into an Ark server, pay and receive freely, and move funds back on-chain whenever you like.',
+    hiwArk2: 'The server can never take your money: every coin you hold in the Ark comes with a pre-signed escape route, and the wallet can put it back on-chain even if the server disappears (“Exit on-chain without the server” in Settings — it takes a while and needs a little on-chain balance for fees, but it needs nobody’s permission).',
+    hiwArk3: 'The housekeeping: Ark coins expire after some weeks, so refresh them (Settings) before then — a wallet left untouched past expiry can be swept by the server. Boarding pays a small server fee plus a normal mining fee; paying inside the Ark is free; withdrawing on-chain pays a server fee taken from the amount.',
+    hiwSpTitle: 'Silent payments',
+    hiwSp1: 'Your wallet also has a silent-payment address (sp1…) that never changes and is safe to share publicly — every payment to it lands at a fresh on-chain address nobody can link to you. Finding those payments uses an indexer service, configurable (or self-hostable) in Settings.',
+    hiwGiftsTitle: 'Gifts',
+    hiwGifts1: 'You can gift bitcoin with a link: whoever opens it claims the coins into their own wallet — no app, no signup. On-chain gifts lock the coins until claimed and can be cancelled or reclaimed; Ark gifts claim instantly and free, even into a brand-new empty wallet. A gift can also be locked to a specific nostr account so only they can claim it.',
     hiwTribute: 'The name Hal Wallet is a tribute to Hal Finney (1956–2014).',
     balance: 'Balance',
     pending: 'Pending',